The microarchitecture of trabecular bone is well known to be key to bone strength and thus resistance to fracture. The current methodology for micromorphometry involves the quantitative assessment of parameters such as bone fraction, trabecular thickness, star volume and intercept length on the basis of microphotographs of polished sections of bone by means of stereologic analysis. The hypothesis underlying the proposed work is that nuclear magnetic resonance imaging at microscopic dimensions ("NMR microscopy") is an alternative and potentially superior investigational tool for the derivation of morphometric parameters from the resulting digital images. The suitability of the technique is enhanced by the intrinsically high contrast between the trabeculae and the protons in the marrow spaces. Another unique feature of the technique is its ability to provide measurements in any arbitrary orientation from three-dimensional isotropic data sets by retrospective data rearrangement. The investigators' preliminary work provides evidence for the feasibility of NMR microscopy as a quantitative morphologic analysis method in vitro at 9.4T and in vivo at 1.5T. The principal aim of this project is to further develop and evaluate NMR microscopy for the study of trabecular architecture in vitro on cadaver specimens from the human patella and in vivo in normal subjects at the same anatomic location. For this purpose computer algorithms will be generated for the unbiased measurement of microarchitectural parameters including trabecular area and thickness, trabecular density, star volume and fabric tensor and to validate the resultant parameters against those derived from conventional stereology on anatomic sections. Another aim is to ascertain the statistical association of these parameters in cadaver specimens of human trabecular bone with Young's modulus. A final aim consists of exploring the feasibility of measuring these parameters in vivo on a suitably modified whole-body NMR scanner, the study of the age dependence of these parameters and their correlation with bone mineral density.